1. Field of the Invention
The present invention relates to a video recording and reproducing apparatus in which video heads are traced along a video tape whereby video signals are recorded and reproduced. More specifically, this invention relates to a dual video signal simultaneous recording apparatus for a video cassette tape recorder (hereinafter, referred to as a VCR) in which four video heads are arranged on a head drum at angles of 90.degree. with respect to each other, each of the different two video signals are supplied to said four video heads so that two different video signals are recorded simultaneously on a video tape.
2. Description of the Background Art
Heretofore, a video recording apparatus of a VCR has been, as shown in FIG. 1, structured such that an input video signal VS passes through a recording system 10 which is composed of automatic gain controller 11, low pass filter 12, pre-emphasis 13, frequency modulator 14, color signal pass filter 15, color signal low band converter 16, mixer 17 and record amplifier 18. The input video signal further passes through record/play switches SW1, SW2 and is applied to video heads CH1, CH2 so that it is recorded on a video tape, while in the case of play back, the video signal detected from the video tape by the video heads CH1, CH2 is input through the record/play switches SW1, SW2 to the play back system so that play back is realized.
Considered in more detail, when a video signal VS to be recorded on a video tape is input, said video signal VS is controlled to a predetermined level in gain through the automatic gain controller 11. A luminance signal from this gain controlled video signal VS passes through the low pass filter 12 and pre-emphasis 13 so that a high band portion emphasized thereafter is modulated at the frequency modulator 14 and applied to the mixer 17. The color signal from said gain controlled video signal VS passes through the color signal pass filter 15 and then the color signal low band converter 16 to be converted to a low band signal thereafter which is applied to the mixer 17 and thereby mixed with the luminance signal which is modulated by said frequency modulator 14. The mixed signal is amplified through the record amplifier 18 and passed through the record/play switches SW1, SW2 which are controlled with the record/play control signal REC/PL then applied to the video heads CH1, CH2 so that it is recorded on the track of video tape in helical state.
Thus, in the case where the video signal recorded on a video tape is intended to be played back, the video signal detected from a video tape by video heads CH1, CH2 is input through the record/play switches SW1, SW2 to the play back system so that play back is executed. The above described typifies the conventional video recorder and player.
By the way, in the case where a video tape is driven to run in standard mode, i.e., SP mode, as shown in FIG. 2, a track of predetermined width D1 is formed on the video tape T, and at this moment, if the video heads CH1, CH2 are formed of the same width D1 of track, then the video signal is recorded on or played back from the entire width D1 of track. Practically, however, the video heads CH1, CH2 become to be formed less than the width D1 of the track for a long period mode, i.e., EP mode and LP mode in which a video tape T is driven to run at 1/2 times and 1/3 times the speed relative the standard mode. In accordance with this, the video signal is recorded with approximately about 1/2 degree less width D2 than a width D1 of track on the video tape T, and at this moment, the track of said video tape T becomes to have a predetermined width D3 which is not recorded with a video signal.
However, in the case of this conventional video recording system, since it is constructed on record to a video tape by selecting only one signal source, there has been a disadvantage that dual video source signals are not able to record simultaneously on one video tape.